Haptic for accommodating intraocular lens

ABSTRACT

An intraocular lens is disclosed, with an optic that changes shape in response to a deforming force exerted by the zonules of the eye. A haptic supports the optic around its equator and couples the optic to the capsular bag of the eye. The region of contact between the optic and the haptic extends into the edge of the optic, similar to the interface between a bicycle tire and the rim that holds it in place. The haptic may be stiffer than the optic. The haptic may have the same refractive index as the optic. The haptic may include a saddle-shaped portion in contact with the adjustable optic, with a convex profile along an optical axis; and a concave profile in a plane perpendicular to the optical axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to intraocular lenses, and moreparticularly to accommodating intraocular lenses.

2. Description of the Related Art

A human eye can suffer diseases that impair a patients vision. Forinstance, a cataract may increase the opacity of the lens, causingblindness. To restore the patients vision, the diseased lens may besurgically removed and replaced with an artificial lens, known as anintraocular lens, or IOL. An IOL may also be used for presbyopic lensexchange.

The simplest IOLs have a single focal length, or, equivalently, a singlepower. Unlike the eye's natural lens, which can adjust its focal lengthwithin a particular range in a process known as accommodation, thesesingle focal length IOLs cannot generally accommodate. As a result,objects at a particular position away from the eye appear in focus,while objects at an increasing distance away from that position appearincreasingly blurred.

An improvement over the single focal length IOLs is an accommodatingIOL, which can adjust its power within a particular range. As a result,the patient can clearly focus on objects in a range of distances awayfrom the eye, rather than at a single distance. This ability toaccommodate is of tremendous benefit for the patient, and more closelyapproximates the patient's natural vision than a single focal lengthIOL.

When the eye focuses on a relatively distant object, the lens power isat the low end of the accommodation range, which may be referred to asthe “far” power. When the eye focuses on a relatively close object, thelens power is at the high end of the accommodation range, which may bereferred to as the “near” power. The accommodation range or add power isdefined as the near power minus the far power. In general, anaccommodation range of 2 to 4 diopters is considered sufficient for mostpatients.

The human eye contains a structure known as the capsular bag, whichsurrounds the natural lens. The capsular bag is transparent, and servesto hold the lens. In the natural eye, accommodation is initiated by theciliary muscle and a series of zonular fibers, also known as zonules.The zonules are located in a relatively thick band mostly around theequator of the lens, and impart a largely radial force to the capsularbag that can alter the shape and/or the location of the natural lens andthereby change its effective power.

In a typical surgery in which the natural lens is removed from the eye,the lens material is typically broken up and vacuumed out of the eye,but the capsular bag is left intact. The remaining capsular bag isextremely useful for an accommodating intraocular lens, in that theeye's natural accommodation is initiated at least in part by the zonulesthrough the capsular bag. The capsular bag may be used to house anaccommodating IOL, which in turn can change shape and/or shift in somemanner to affect the power and/or the axial location of the image.

The IOL has an optic, which refracts light that passes through it andforms an image on the retina, and a haptic, which mechanically couplesthe optic to the capsular bag. During accommodation, the zonules exert aforce on the capsular bag, which in turn exerts a force on the optic.The force may be transmitted from the capsular bag directly to theoptic, or from the capsular bag through the haptic to the optic.

A desirable optic for an accommodating IOL is one that distorts inresponse to a squeezing or expanding radial force applied largely to theequator of the optic (i.e., by pushing or pulling on or near the edge ofthe optic, circumferentially around the optic axis). Under the influenceof a squeezing force, the optic bulges slightly in the axial direction,producing more steeply curved anterior and/or posterior faces, andproducing an increase in the power of the optic. Likewise, an expandingradial force produces a decrease in the optic power by flattening theoptic. This change in power is accomplished in a manner similar to thatof the natural eye and is well adapted to accommodation. Furthermore,this method of changing the lens power reduces any undesirable pressuresexerted on some of the structures in the eye.

One challenge in implementing such an optic is designing a suitablehaptic to couple the optic to the capsular bag. The haptic should allowdistortion of the optic in an efficient manner, so that a relativelysmall ocular force from the ciliary muscle, zonules, and/or capsular bagcan produce a relatively large change in power and/or axial location ofthe image. This reduces fatigue on the eye, which is highly desirable.

Accordingly, there exists a need for an intraocular lens having a hapticwith increased efficiency in converting an ocular force to a change inpower and/or a change in axial location of the image.

SUMMARY OF THE INVENTION

An embodiment is an intraocular lens for implantation in a capsular bagof an eye, comprising an adjustable optic; and a haptic protruding intothe adjustable optic. The haptic is configured to transmit forces toalter at least one of the shape or the thickness of the adjustableoptic.

A further embodiment is an intraocular lens for implantation in acapsular bag of an eye, comprising an adjustable optic having an opticstiffness and an optic refractive index; and a haptic having a hapticstiffness and a haptic refractive index for coupling the adjustableoptic to the capsular bag. The haptic stiffness is greater than theoptic stiffness. The haptic refractive index is essentially equal to theoptic refractive index.

A further embodiment is a method of adjusting the focus of anintraocular lens having an adjustable optic having an annular recess,comprising applying a deforming force through a haptic in contact withthe annular recess of the adjustable optic; and altering at least oneparameter of the adjustable optic in response to the deforming force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan drawing of a human eye having an implanted intraocularlens, in an accommodative or “near” state.

FIG. 2 is a plan drawing of the human eye of FIG. 1, in adisaccommodative or “far” state.

FIG. 3 is an isometric drawing of a haptic coupled to an optic.

FIG. 4 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 5 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 6 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 7 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 8 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 9 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 10 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 11 is a cross-sectional plan drawing of a haptic segment coupled toan optic segment.

FIG. 12 is a cross-section drawing of a haptic.

FIG. 13 is a cross-sectional drawing of the haptic of FIG. 12, with anoptic.

FIG. 14 is the cross-section drawing of the haptic and optic of FIG. 13,with additional hidden lines.

FIG. 15 is an end-on cross-sectional drawing of the haptic and optic ofFIG. 13.

FIG. 16 is a plan drawing of the haptic of FIG. 12.

FIG. 17 is a plan drawing of the haptic of FIG. 16, with an optic.

FIG. 18 is the cross-section drawing of the haptic and optic of FIG. 17,with additional hidden lines.

FIG. 19 is a plan drawing of a haptic.

FIG. 20 is a plan drawing of the haptic of FIG. 19, with an optic.

FIG. 21 is the plan drawing of the haptic and optic of FIG. 20, withadditional hidden lines.

FIG. 22 is a top-view plan drawing of a haptic with an optic.

FIG. 23 is a side-view plan drawing of the haptic and optic of FIG. 22.

FIG. 24 is a side-view cross-sectional drawing of the haptic and opticof FIG. 22.

FIG. 25 is a plan drawing of the haptic and optic of FIG. 22.

FIG. 26 is a cross-sectional drawing of the haptic and optic of FIG. 22.

FIG. 27 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 28 is a cross-sectional isometric drawing of a haptic segmentcoupled to an optic segment.

FIG. 29 is a isometric drawing of the geometry of a saddle-shapedhaptic.

DETAILED DESCRIPTION OF THE DRAWINGS

In a healthy human eye, the natural lens is housed in a structure knownas the capsular bag. The capsular bag is driven by a ciliary muscle andzonular fibers (also known as zonules) in the eye, which can compressand/or pull on the capsular bag to change its shape. The motions of thecapsular bag distort the natural lens in order to change its powerand/or the location of the lens, so that the eye can focus on objects atvarying distances away from the eye in a process known as accommodation.

For some people suffering from cataracts, the natural lens of the eyebecomes clouded or opaque. If left untreated, the vision of the eyebecomes degraded and blindness can occur in the eye. A standardtreatment is surgery, during which the natural lens is broken up,removed, and replaced with a manufactured intraocular lens. Typically,the capsular bag is left intact in the eye, so that it may house theimplanted intraocular lens.

Because the capsular bag is capable of motion, initiated by the ciliarymuscle and/or zonules, it is desirable that the implanted intraocularlens change its power and/or location in the eye in a manner similar tothat of the natural lens. Such an accommodating lens may produce vastlyimproved vision over a lens with a fixed power and location that doesnot accommodate.

FIG. 1 shows a human eye 10, after an accommodating intraocular lens hasbeen implanted. Light enters from the left of FIG. 1, and passes throughthe cornea 12, the anterior chamber 14, the iris 16, and enters thecapsular bag 18. Prior to surgery, the natural lens occupies essentiallythe entire interior of the capsular bag 18. After surgery, the capsularbag 18 houses the intraocular lens, in addition to a fluid that occupiesthe remaining volume and equalizes the pressure in the eye. Theintraocular lens is described in more detail below. After passingthrough the intraocular lens, light exits the posterior wall 20 of thecapsular bag 18, passes through the posterior chamber 32, and strikesthe retina 22, which detects the light and converts it to a signaltransmitted through the optic nerve 24 to the brain.

A well-corrected eye forms an image at the retina 22. If the lens hastoo much or too little power, the image shifts axially along the opticalaxis away from the retina, toward or away from the lens. Note that thepower required to focus on a close or near object is more than the powerrequired to focus on a distant or far object. The difference between the“near” and “far” powers is known typically as the range ofaccommodation. A normal range of accommodation is about 4 diopters,which is considered sufficient for most patients.

The capsular bag is acted upon by the ciliary muscle 25 via the zonules26, which distort the capsular bag 18 by stretching it radially in arelatively thick band about its equator. Experimentally, it is foundthat the ciliary muscle 25 and/or the zonules 26 typically exert a totalocular force of up to about 10 grams of force, which is distributedgenerally uniformly around the equator of the capsular bag 18. Althoughthe range of ocular force may vary from patient to patient, it should benoted that for each patient, the range of accommodation is limited bythe total ocular force that can be exert. Therefore, it is highlydesirable that the intraocular lens be configured to vary its power overthe full range of accommodation, in response to this limited range ofocular forces. In other words, it is desirable to have a relativelylarge change in power for a relatively small driving force.

Because the zonules' or ocular force is limited, it is desirable to usea fairly thin lens, compared to the full thickness of the capsular bag.In general, a thin lens may distort more easily than a very thick one,and may therefore convert the ocular force more efficiently into achange in power. In other words, for a relatively thin lens, a lowerforce is required to cover the full range of accommodation.

Note that there may be an optimum thickness for the lens, which dependson the diameter of the optic. If the lens is thinner than this optimumthickness, the axial stiffness becomes too high and the lens changespower less efficiently. In other words, if the edge thickness isdecreased below its optimal value, the amount of diopter power changefor a given force is decreased. For instance, for an optic having adiameter of 4.5 mm, an exemplary ideal edge thickness may be about 1.9mm, with edge thicknesses between about 1.4 mm and about 2.4 havingacceptable performance as well.

Note that the lens may be designed so that its relaxed state is the“far” condition (sometimes referred to as “disaccommodative biased”),the “near” condition (“accommodative biased”), or some condition inbetween the two.

The intraocular lens itself generally has two components: an optic 28,which is made of a transparent, deformable and/or elastic material, anda haptic 30, which holds the optic 28 in place and mechanicallytransfers forces on the capsular bag 18 to the optic 28. The haptic 30may have an engagement member with a central recess that is sized toreceive the peripheral edge of the optic 28.

When the eye 10 focuses on a relatively close object, as shown in FIG.1, the zonules 26 relax and the capsular bag 18 returns to its naturalshape in which it is relatively thick at its center and has more steeplycurved sides. As a result of this action, the power of the lensincreases (i.e., one or both of the radii of curvature can decrease,and/or the lens can become thicker, and/or the lens may also moveaxially), placing the image of the relatively close object at the retina22. Note that if the lens could not accommodate, the image of therelatively close object would be located behind the retina, and wouldappear blurred.

FIG. 2 shows a portion of an eye 40 that is focused on a relativelydistant object. The cornea 12 and anterior chamber 14 are typicallyunaffected by accommodation, and are substantially identical to thecorresponding elements in FIG. 1. To focus on the distant object, theciliary muscle 45 contracts and the zonules 46 retract and change theshape of the capsular bag 38, which becomes thinner at its center andhas less steeply curved sides. This reduces the lens power by flattening(i.e., lengthening radii of curvature and/or thinning) the lens, placingthe image of the relatively distant object at the retina (not shown).

For both the “near” case of FIG. 1 and the “far” case of FIG. 2, theintraocular lens itself deforms and changes in response to thedistortion of the capsular bag. For the “near” object, the haptic 30compresses the optic 28 at its edge, increasing the thickness of theoptic 28 at its center and more steeply curving its anterior face 27and/or its posterior face 29. As a result, the lens power increases. Forthe “far” object, the haptic 50 expands, pulling on the optic 48 at itsedge, and thereby decreasing the thickness of the optic 48 at its centerand less steeply curving (e.g., lengthening one or both radius ofcurvature) its anterior face 47 and/or its posterior face 49. As aresult, the lens power decreases.

Note that the specific degrees of change in curvature of the anteriorand posterior faces depend on the nominal curvatures. Although theoptics 28 and 48 are drawn as bi-convex, they may also be plano-convex,meniscus or other lens shapes. In all of these cases, the optic iscompressed or expanded by essentially forces by the haptic to the edgeand/or faces of the optic. In addition, the may be some axial movementof the optic. In some embodiments, the haptic is configured to transferthe generally symmetric radial forces symmetrically to the optic todeform the optic in a spherically symmetric way. However, in alternateembodiments the haptic is configured non-uniformly (e.g., havingdifferent material properties, thickness, dimensions, spacing, angles orcurvatures), to allow for non-uniform transfer of forces by the hapticto the optic. For example, this could be used to combat astigmatism,coma or other asymmetric aberrations of the eye/lens system. The opticsmay optionally have one or more diffractive elements, one or moremultifocal elements, and/or one or more aspheric elements.

FIG. 3 shows a deformable optic with an exemplary haptic, shown inisometric view and removed from the eye. The view of FIG. 3 shows thatthe haptic extends a full 360 degrees azimuthally around the edge of theoptic, which is not seen in the cross-sectional view of FIGS. 1 and 2.

The exemplary haptic of FIG. 3 has various segments or filaments, eachof which extends generally in a plane parallel to the optical axis ofthe lens. For the exemplary haptic of FIG. 3, the segments are joined toeach other at one end, extend radially outward until they contact thecapsular bag, then extend radially inward until they contact the edge ofthe optic. At the edge of the optic, the haptic segments may remainseparate from each other, as shown in FIG. 3, or alternatively some orall segments may be joined together. Any or all of the width, shape andthickness of the segments may optionally vary along the length of thesegments. The haptic may have any suitable number of segments, includingbut not limited to, 4, 6, 8, 10, 12, 14, and 16.

Note that the region of contact between the optic and the haptic in FIG.3 extends into the edge of the optic, similar to the interface between abicycle tire and the rim that holds it in place. This region of contactbetween the haptic and the optic is described and shown in much greaterdetail in the text and figures that follow.

FIG. 4 shows an azimuthal slice of an optic 41 and a haptic 42. Althoughonly two segments of the haptic 42 are shown in FIG. 4, it will beunderstood that haptic 42 may extend fully around the equator of theoptic 41.

Of particular note is the interface between the haptic 42 and the optic41. The optic 41 in FIG. 4 has an annular recess 43 around its edge, andthe haptic 42 extends or protrudes into this annular recess, instead ofmerely contacting the optic at a cylindrical edge parallel to theoptical axis.

This protrusion into the edge of the optic may allow for greatertransfer of forces from the capsular bag, through the haptic, to theoptic. There may be a greater coupling of these forces to the anteriorand/or posterior surfaces of the optic, which may result in moredistortion or deforming of these surfaces for a given distorting force.As a result, the limited capsular bag force may produce a greaterdistortion of the optic, and, therefore, a larger change in power and/ora larger axial translation of the image at the retina.

The optic 41 is made from a relatively soft material, so that it candistort or change shape readily under the limited deforming forceinitiated by the capsular bag and transmitted through the haptic 42. Anexemplary material is a relatively soft silicone material, althoughother suitable materials may be used as well. The stiffness of the optic41 may be less than 500 kPa, or preferably may be between 0.5 kPa and500 kPa, or more preferably may be between 25 kPa and 200 kPa, or evenmore preferably may be between 25 kPa and 50 kPa.

In contrast with the optic 41, the haptic 42 is made from a relativelystiff material, so that it can efficiently transmit the deforming forcesfrom the capsular bag to the optic 41. An exemplary material is arelatively stiff silicone material, although other suitable materialsmay be used as well, such as acrylic, polystyrene, or clearpolyurethanes. The haptic 42 may preferably be stiffer than the optic41. The stiffness of the haptic 42 may be greater than 500 kPa, orpreferably may be greater than 3000 kPa.

Because the haptic 42 extends into the optic 41 in a region around itscircumference, it also may extend into the clear aperture of the optic41. For this reason, the haptic may preferably be transparent or nearlytransparent, so that it does not substantially block any lighttransmitted through the lens.

In addition, it is desirable that the interface between the optic 41 andthe haptic 42 does not produce any significant reflections, which wouldproduce scattered light within the eye, and would appear as a haze tothe patient. A convenient way to reduce the reflections from theinterface is to match the refractive indices of the haptic and the opticto each other.

A simple numerical example shows the effect of mismatch of refractiveindices on reflected power. For a planar interface at normal incidencebetween air (refractive index of 1) and glass (refractive index of 1.5),4% of the incident power is reflected at the interface. For such aninterface between air and glass, there is no attempt to match refractiveindices, and this 4% reflection will merely provide a baseline forcomparison. If, instead of 1 and 1.5, the refractive indices differ by4%, such as 1.5 and 1.56 or 1.5 and 1.44, there is a 0.04% reflection,or a factor of 100 improvement over air/glass. Finally, if therefractive indices differ by only 0.3%, such as 1.5 and 1.505 or 1.5 and1.495, there is a 0.00028% reflection, or a factor of over 14000improvement over air/glass. In practice, tolerances such as the 0.3%case may be achievable, and it is seen that a negligible fraction ofpower may be reflected at the interface between a haptic and an opticwhose refractive indices differ by 0.3%. Note that the above base valueof 1.5 was chosen for simplicity, and that the haptic and optic may haveany suitable refractive index.

It is desirable that the refractive indices of the haptic and optic beessentially the same. For the purposes of this document, “essentiallythe same” may mean that their refractive indices are equal to each otherat a wavelength within the visible spectrum (i.e., between 400 nm and700 nm). Note that the haptic and optic may optionally have differentdispersions, where the refractive index variation, as a function ofwavelength, may be different for the haptic and the optic. In otherwords, if the refractive indices of the haptic and optic are plotted asa function of wavelength, they may or may not have different slopes, andif the two curves cross at one or more wavelengths between 400 nm and700 nm, then the refractive indices may be considered to be essentiallythe same or essentially equal.

The exemplary haptic 42 has segments that are not joined at the edge ofthe optic 41, and has a generally uniform thickness throughout. Notethat these two qualities of the haptic may be varied, as shown in FIGS.5 through 8.

In FIG. 5, the segments of the haptic 52 are joined at the edge of theoptic 51. The optic has an annular recess 53, analogous to annularrecess 43 of FIG. 4. Note that at the edge of the optic, the hapticsegments need not be all joined or all separate, but may be joined inadjacent pairs or in any other suitable scheme.

In FIG. 6, the haptic 62 has a variation in thickness along the edge ofthe optic 61, so that the side opposite the annular recess 63 isessentially flat.

In FIG. 7, the haptic 72 has a variation in thickness along the edge ofthe optic 71, so that the side opposite the annular recess 73 is convex.

In FIG. 8, the haptic 82 has an increasing thickness approaching theannular recess 83 of the optic 81.

In FIGS. 4 through 8, each haptic is made from a single, relativelystiff material, and each optic is made from a single, relatively softmaterial. As an alternative, other materials having differentstiffnesses may be introduced.

For instance, FIG. 9 shows an optic 91 made from a soft material, ahaptic 92 made from a stiff material 94, and a third material 95 that isstiffer than the haptic stiff material 94. Alternatively, the thirdmaterial 95 may be less stiff than the haptic stiff material 94. In thisexample, the third material 95 is in contact with the optic 91 at itsannular recess 93. For the purposes of this document, such a thirdmaterial 95 may be considered to be part of the haptic 92, although inpractice it may optionally be manufactured as part of the optic 91.Alternatively, there may be one or more materials used for the hapticand/or the optic, which may have the same or different stiffnesses.

In FIGS. 4 through 9, each optic has an annular recess with a generallysmooth, curved, concave profile, along a direction parallel to theoptical axis of the lens. (Similarly, each corresponding haptic has agenerally smooth, curved, convex profile, along a direction parallel tothe optical axis of the lens.) As an alternative, the profile need notbe generally smooth, and/or need not be curved.

For instance, the optic 101 of FIG. 10 has an annular recess 103 with aconcave profile that is not smooth but has corners, and is not curvedbut has straight portions. (Similarly, the haptic 102 has a convexprofile with corners and straight portions.) In this case, one of thestraight portions 104 is parallel to the optical axis of the lens, andthe other two straight portions 105 and 106 are inclined with respect toa plane perpendicular to the optical axis.

In FIG. 10, the deepest portion of the profile falls along the straightportion 103, although it may fall at a particular point rather thanalong a full line. The particular point may be a corner, or may be apoint along a smooth curve. For FIG. 10, the deepest portion passesthrough the midpoint of the lens (i.e., the plane halfway between theanterior and posterior surfaces of the optic).

As an alternative, the deepest portion of the profile may be locatedaway from the midpoint of the lens, and may be located closer to eitherthe anterior or posterior surfaces of the optic. For instance, FIG. 11shows a cross-section of an optic 111 and a portion of a haptic withsuch an asymmetric deepest portion 114. A potential advantage of suchasymmetry is that the deformation of the surfaces may be tailored morespecifically than with a symmetric profile, so that one surface maydeform more than the other under a deforming force exerted by thehaptic. This may be desirable for particular optic shapes.

In FIGS. 4 through 10, each of the haptics is attached to the optic atonly one end. As an alternative, the haptic may be attached to the opticat both ends. For instance, haptic 272 of FIG. 27 attaches to optic 271at both ends. Optic 271 has annular recess 273, analogous with theannular recesses of FIGS. 4 through 11. Furthermore, the interior regionof the haptic, shown as hollow in FIG. 27, may optionally be filled witha liquid or a gel having particular mechanical properties.

FIG. 28 shows a haptic 282 similar to that in FIG. 27, but with avariation in thickness in the region opposite the annular recess 283 ofthe optic 281. Similarly, the thickness may optionally be varied at anypoint on the haptic 282.

For further clarification of the previous geometries, FIG. 29 shows asmall portion of a haptic 292 along with some geometrical constructs. InFIG. 29, the optical axis of the lens is vertical. The upper ellipse 294corresponds to the circumference of the anterior (or posterior) surfaceof the lens, and the lower ellipse 295 corresponds to the circumferenceof the posterior (or anterior) surface of the lens. The haptic 292 has aportion 296 that may be considered saddle-shaped or hyperbolic, with aconvex profile 297 along a direction parallel to the optical axis of thelens, and a concave profile 298 in a plane perpendicular to the opticalaxis of the lens. Similarly, the optic (not shown) would have acorresponding annular recess that contacts a portion 296 of the haptic.Although the convex profile 297 and concave profile 298 are shown assmooth and continuous curves, they may alternatively have one or morestraight segments, and/or may alternatively be asymmetric with respectto the anterior or posterior surfaces of the optic.

It may be beneficial to describe in words the interface between thehaptic and the optic for the various lenses shown in the figures.Consider a radial plane to be a plane that includes the optical axis ofthe lens. The intersection of the radial plane with the haptic/opticinterface of the lens forms a so-called “cross-sectional curve.” Theendpoints of the cross-sectional curve are to be referred to as anteriorand posterior endpoints, respectively.

As seen from the figures, the cross-sectional curve protrudes into theoptic. We may define this protrusion more precisely by comparing thecross-sectional curve with a so-called “cylindrical edge” of the optic,which is taken to be a line connecting the anterior and posteriorendpoints of the cross-sectional curve. Note that this “cylindricaledge” need not be truly parallel to the optical axis. “Protrusion intothe optic” may therefore be interpreted in any or all of the followingmanners:

(1) The separation between the cross-sectional curve and the opticalaxis is less than the separation between the cylindrical edge and theoptical axis, for all points between the anterior and posteriorendpoints. This includes the designs of FIGS. 4-11, 27 and 28, andincludes additional designs in which the entire cross-sectional curveprotrudes into the optic.

(2) The separation between the cross-sectional curve and the opticalaxis is less than the separation between the cylindrical edge and theoptical axis, for at least one point between the anterior and posteriorendpoints. This also includes the designs of FIGS. 4-11, 27 and 28, butmay include additional designs in which only a portion of thecross-sectional curve protrudes into the optic.

As also seen from the figures, the cross-sectional curve may take onvarious shapes. For all of the designs shown in the figures, thecross-sectional curve extends inward toward the optical axis as onemoves away from the anterior endpoint, reaches a “local minimum” or a“deepest portion” at which the cross-sectional curve is at its closestto the optical axis, then extends outward away from the optical axis asone approaches the posterior endpoint. Differences arise among thevarious designs in the character and location of the deepest portion, aswell as the local curvature of the cross-sectional curve. Three suchcategories of differences are detailed below; these three categories arenot intended to be all-inclusive.

(1) The cross-sectional curve does not contain any corners,discontinuities, or straight segments. This includes the designs ofFIGS. 4-9, 27 and 28. Note that the “deepest portion” occurs at only onepoint along the cross-sectional curve. This category of curve may bereferred to as a “continuous curve”. Note that a continuous curve mayoptionally extend in part outside the so-called “cylindrical edge” ofthe optic; the designs shown in the figures extend only into thecylindrical edge of the optic.

(2) The cross-sectional curve may contain at least one straight segment,but does not contain any corners or discontinuities. The straightsegment may be located anywhere along the cross-sectional curve. Thestraight segment may be inclined with respect to the optical axis, ormay be parallel to the optical axis. The straight segment may also beparallel to the optical axis at the “deepest portion,” so that thedeepest portion may have a finite spatial extent, rather than a singlelocation.

(3) The cross-sectional curve may contain at least one straight segment,and may contain at least one corner, but does not contain anydiscontinuities. This includes the designs of FIGS. 10 and 11, whicheach contain three straight segments and two corners. In each of thedesigns of FIGS. 10 and 11, as one moves away from the anteriorendpoint, the cross-section curve contains a straight segment extendingtoward the optical axis, followed by a straight segment parallel to theoptical axis, followed by a straight segment extending away from theoptical axis as one approaches the posterior endpoint. For the designsof FIGS. 10 and 11, the middle straight segment is the “deepest portion”of the curve, which is bounded on both sides by a segment that isinclined with respect to the optical axis and is also inclined withrespect to both the anterior and posterior surfaces of the optic. InFIG. 10, the middle portion 104 is bounded on either side by straightportions 105 and 106, and is symmetrically located between the anteriorand posterior surfaces. In FIG. 11, the middle portion 114 is alsobounded by straight portions, but is asymmetrically located between theanterior and posterior surfaces.

The following paragraphs describe a series of simulation results thatcompare the performance of the haptic designs of FIGS. 4-8 to each otherand to a baseline design.

A series of finite element calculations were performed, each withidentical materials, identical shapes for the optic, identical shapesfor the annular recess in the optic, and identical shapes for the hapticportion that contacts the capsular bag of the eye. The haptic thicknesswas varied to correspond to the cases of FIGS. 4 through 8. Finally abaseline case was calculated, in which the convex profile (analogous toelement 297 in FIG. 29) was not convex, but was planar; in this baselinecase, the haptic did not protrude or extend into the edge of theadjustable optic. The haptic thickness of the baseline case was the sameas for FIG. 4.

The results of the calculations are expressed as a power change indiopters, where a larger number is better. The baseline case produced apower change of 2.94 diopters. The configuration of FIG. 4 produced apower change of 5.24 diopters. The configuration of FIG. 5 produced apower change of 4.99 diopters. The configuration of FIG. 6 produced apower change of 4.96 diopters. The configuration of FIG. 7 produced apower change of 5.62 diopters. The configuration of FIG. 8 produced apower change of 9.24 diopters. These power change values are all greaterthan the baseline case, and all exceed the 4 diopter value that isgenerally accepted as a full range of accommodation.

FIGS. 12 through 18 show an exemplary haptic 120 in various plan andcross-sectional views, both with and without an optic 130. FIG. 12 is across-section drawing of a haptic 120. FIG. 13 is a cross-sectionaldrawing of the haptic of FIG. 12, with an optic 130. FIG. 14 is thecross-section drawing of the haptic 120 and optic 130 of FIG. 13, withadditional hidden lines. FIG. 15 is an end-on cross-sectional drawing ofthe haptic 120 and optic 130 of FIG. 13. FIG. 16 is a plan drawing ofthe haptic 120 of FIG. 12. FIG. 17 is a plan drawing of the haptic 120of FIG. 16, with an optic 130. FIG. 18 is the cross-section drawing ofthe haptic 120 and optic 130 of FIG. 17, with additional hidden lines.

The haptic 120 of FIGS. 12 through 18 has eight filaments denoted byelements 121 a through 121 h. Alternatively, the haptic 120 may havemore or fewer than eight filaments (e.g., 3 filaments, 4 filaments, or16 filaments). The filaments 121 a-h may be connected at their outermostedge and may be unconnected at their innermost edge.

Note that the filaments 121 a-h may vary in size along their lengths,from the innermost edge 123 to the ends of the filament adjacent to theoutermost edge 122 of the haptic 120. In particular, the filaments 121a-h may increase in cross-sectional dimensions with radial distance awayfrom the center of the lens. In a direction parallel to the optical axis(vertical in FIG. 12), the outermost extent of the haptic filaments,denoted by length 129, may be larger than the innermost extent of thehaptic filaments, denoted by dimension 128. Alternatively, the length129 may be equal to or less than length 128. Similarly, in a directionperpendicular to the optical axis (essentially in the plane of thelens), the filaments may be effectively wedge-shaped, with a greaterradial extent at the outer edge than at the inner edge. Thecross-section of each filament may be symmetric with respect to theplane of the lens, as shown in FIG. 12. Alternatively, the cross-sectionof one or more filaments may be asymmetric with respect to the plane ofthe lens, with differing amounts of material on anterior and posteriorsides of the filament.

The outermost edge 122 of the haptic 120 mechanically couples theintraocular lens to the capsular bag of the eye. The haptic 120 mayreceive an optic 130 in its central region, which may be molded directlyonto the haptic 120. Alternatively, the optic may be manufacturedseparately from the haptic, then attached to the haptic.

The haptic 120 may have an optional lip or ridge 124 on one or both ofthe anterior and posterior faces, so that if an optic is molded directlyonto the haptic 120, the optic resides in the central portion of thehaptic within the lip 124. The lip 124 may be circularly symmetric onboth faces of the haptic, as shown in FIGS. 12 through 18.Alternatively, the lip 124 may have a different radius on one or morefilaments, so that optic material may extend out different radialdistances along particular filaments. As a further alternative, the lip124 may have different radii on the anterior and posterior faces of thehaptic 120.

Once the optic 130 is formed on, attached to, or placed within thehaptic 120, the haptic 120 protrudes into the edge 131 of the optic 130.For the specific design of FIGS. 12 through 18, portions of eachfilament 121 a-h extend into the edge 131 of the optic 130, with theanterior and posterior faces of the optic 130 surrounding and/orencompassing the haptic filaments 121 a-h in the central portiondemarcated by the lip 124.

For a cross-section of the filaments 121 a-h, taken in a plane parallelto the optical axis of the lens (vertical in FIGS. 12 through 18), thecross-section has a particular profile that extends into the edge 131 ofthe optic 130. The profile may contain one or more straight and/orcurved portions, and may have a deepest portion at one or more points oralong a straight segment. For instance, the profile in FIGS. 12 and 15has a generally straight portion 125 extending generally radiallyinward, followed by a generally straight portion 126 extending generallyparallel to the optical axis, followed by a generally straight portion127 extending generally radially outward. The generally straightportions 125, 126 and 127 may optionally have one or more roundedportions 151 between them. Straight portions 125 and 127 may begenerally parallel to each other, or may be generally inclined withrespect to each other. The generally straight portion 126 may begenerally parallel to the optical axis, as in FIGS. 12 and 15, or mayalternatively be inclined with respect to the optical axis. The deepestportion of the profile of FIGS. 12 and 15 may be the straight portion126. The profile made up of segments 125, 126 and 127 shown in FIGS. 12and 15 may be generally convex in a direction parallel to the opticalaxis of the lens.

Referring to FIG. 15, the axial thickness (i.e., along an axis parallelto the optical axis passing through the center of the optic 130) of theportions of the haptic 120 disposed within the optic 130 may be selectedto control the amount and/or distribution of an ocular force acting onthe intraocular lens 240. For example, in some embodiments, theperformance (e.g., the change Diopter power of the optic 130 betweenaccommodative and disaccommodative configurations) increases as the edgethickness increases. In such embodiments, other design constraints(e.g., optical performance or physical constraints of the eye) may,however, place an upper limit on the maximum optic edge thickness. Insome embodiments, the portion of the haptic 120 inside the optic 130 hasa maximum axial thickness that is at least one half a maximum axialthickness of the optic 130 along the optical axis, as clearlyillustrated in FIG. 15. In other embodiments, the ring portion 246 ofthe haptic 244 has a maximum axial thickness that is at least 75% of amaximum axial thickness of the central zone. The advantages of the axialthickness the protruding portions of the haptic 120 may also be appliedto other embodiments of the invention discussed herein.

In certain embodiments, the optic 130 is a multifocal optic. Forexample, the portion of the optic 130 between the ends 126 of the haptic120 may comprise a first zone having a first optical power and theportion of the optic 130 into which the filaments 121 protrude maycomprise a second zone having a second optic power that is differentfrom the first optical power. In some embodiments, the optic 130 maychange from a monofocal optic to a multifocal optic, depending upon theamount of ocular force on the haptic 120 and/or the state ofaccommodation of the eye into which the intraocular lens is inserted.

If the optic 130 may be molded directly onto the haptic 120, the haptic120 may be first expanded or contracted radially by an external force,prior to molding. The optic 130 may then be molded directly onto theexpanded or contracted haptic 120. After molding, the external force maybe removed, and the haptic may return to its original size or fairlyclose to its original size, forming radial stresses within the optic130.

It is desirable that the haptic be made from a stiffer material than theoptic, so that any distorting forces induced by the zonules or capsularbag are transmitted efficiently through the haptic to the optic, andefficiently change the shape of the optic. It is also desirable that thehaptic and the optic have similar or essentially equal refractiveindices, which would reduce any reflections at the interfaces betweenthe haptic and the optic.

FIGS. 19 through 21 show another exemplary haptic 190 in various planviews, both with and without an optic 200. FIG. 19 is a plan drawing ofa haptic 190. FIG. 20 is a plan drawing of the haptic 190 of FIG. 19,with an optic 200. FIG. 21 is the plan drawing of the haptic 190 andoptic 200 of FIG. 20, with additional hidden lines.

The haptic 190 of FIGS. 19 through 21 has eight filaments denoted byelements 191 a through 191 h. Alternatively, the haptic 190 may havemore or fewer than eight filaments. Filaments 191 a-h may havenon-uniformities along their lengths, such as width variations, heightvariations, and/or holes 192 a-h.

The holes 192 a-h may desirably alter the mechanical properties of therespective filaments, so that a given zonular force may be transmittedefficiently into a distortion of the optic. The holes 192 a-h may betriangular in shape, or may be any other suitable shape, such as round,square, rectangular, polygonal, and may optionally have one or morerounded corners and/or edges. Each hole may optionally vary in profilealong its depth. There may optionally be more than one hole perfilament. There may optionally be differing numbers of holes fordifferent filaments. There may optionally be differently-shaped holes onthe same filament.

Unlike the filaments 121 a-h of FIGS. 12 through 18, the filaments 191a-h are connected at both their outermost edge and their innermost edge.The filaments 191 a-h are joined at an outer annular ring 193 and aninner annular ring 194. The inner annular ring 194 may lie within thecircumference of the optic 200, as in FIGS. 19 through 21.Alternatively, the inner annular ring 194 may lie outside thecircumference of the optic 200, or may straddle the circumference of theoptic 200.

The dimensions of the inner annular ring 194, specifically, the innerand outer diameters of the inner annular ring 194, may be determined inpart by the stiffness of the haptic 190 and/or the stiffness of theoptic 200. For instance, a stiffer haptic may require relatively littlematerial, and the ratio may be fairly close to 1. Alternatively, a lessstiff haptic may require more material, and the ratio may deviatesignificantly from 1.

FIGS. 22 through 26 show another exemplary haptic 220 in various planviews, with an optic 230. FIG. 22 is a top-view plan drawing of a haptic220 with an optic 230. FIG. 23 is a side-view plan drawing of the haptic220 and optic 230 of FIG. 22. FIG. 24 is a side-view cross-sectionaldrawing of the haptic 220 and optic 230 of FIG. 22. FIG. 25 is a plandrawing of the haptic 220 and optic 230 of FIG. 22. FIG. 26 is across-sectional drawing of the haptic 220 and optic 230 of FIG. 22.

The haptic 220 of FIGS. 22 through 26 has a more complex shape than thehaptics shown in FIGS. 12 through 21. The haptic 220 has eight filaments221 a-h, each of which has one end attached to an inner annular ring 222and has the opposite end attached to an outer annular ring 223.Alternatively, the haptic 220 may have more or fewer than eightfilaments. In contrast with the haptics of FIGS. 12 through 21, thehaptic 220 contacts the capsular bag of the eye at one or more pointsalong the filaments 221 a-h between the inner and outer annular rings222 and 223. In some embodiments, the filaments 221 a-h may loop back onthemselves, and may contact the capsular bag at one or more extremaalong the loop, rather than at the outer annular ring 223.

As with the inner annular ring 194 of FIGS. 19 through 21, the innerannular ring 222 may lie inside the circumference of the optic 230, oncethe optic 230 is placed within the haptic 220, may lie outside thecircumference of the optic 230, or may straddle the circumference of theoptic 230.

In some embodiments, such as the disc-shaped intraocular lenses shown inFIGS. 12 through 21, the haptic filaments engage an equatorial region ofthe capsular bag. In many of these embodiments, the optical power ofintraocular lens may be selected to provide a disaccommodative bias,although some embodiments may alternatively provide an accommodativebias.

In other embodiments, the haptic filaments may engage substantially theentire capsular bag, rather than just the equatorial region of thecapsular bag. In some of these embodiments, the filaments may extendgenerally in a plane that includes the optical axis of the lens, andthere may be uncontacted portions of the capsular bag in the regionsbetween the filaments. In many of these embodiments, the intraocularlens has an accommodative bias, although some embodiments mayalternatively use a disaccommodative bias.

For the designs of FIGS. 12 through 26, the haptic may be pre-stressed,and the optic nay then be molded onto or attached to the haptic whilethe haptic is in the pre-stressed state. For instance, the haptic may becompressed or expanded radially prior to placing the optic within thehaptic. The pre-stress may then be removed, and the lens may be allowedto relax to its substantially unstressed state, or a “natural” state.For a haptic that is much stiffer than the optic, the haptic mayexpand/contract by nearly the full compression/expansion amount, and theoptic becomes expanded/compressed about its equator. In its expandedstate, the optic is under radial tension.

This pre-stress may help reduce or eliminate buckling of the optic, ifthe optic is compressed. It may also reduce the need for a thicker opticfor maximizing the power change for a given external force (e.g., anocular force produced by the ciliary muscle, the zonules, and/or thecapsular bag of the eye.) Furthermore, the pre-stress may allow for aso-called “fail-safe” design that allows only a certain amount of powerchange during accommodation; the lens may minimize the power changebeyond a prescribed accommodation range. In addition, the pres-stressmay reduce the amount of force required for a given power change.

The description of the invention and its applications as set forthherein is illustrative and is not intended to limit the scope of theinvention. Variations and modifications of the embodiments disclosedherein are possible, and practical alternatives to and equivalents ofthe various elements of the embodiments would be understood to those ofordinary skill in the art upon study of this patent document. These andother variations and modifications of the embodiments disclosed hereinmay be made without departing from the scope and spirit of theinvention.

1. An intraocular lens for implantation in a capsular bag of an eye,comprising: an adjustable optic having an axial thickness through thecenter thereof; and a haptic including a portion protruding into theadjustable optic, the haptic portion having a maximum axial thicknessthat is at least one half the axial thickness of the adjustable optic;whereby the haptic is configured to transmit forces to alter at leastone of the shape and the thickness of the adjustable optic.
 2. Theintraocular lens of claim 1, wherein the haptic protrudes into the edgeof the adjustable optic.
 3. The intraocular lens of claim 1, wherein thehaptic includes a saddle-shaped portion in contact with the adjustableoptic;
 4. The intraocular lens of claim 3, wherein the saddle-shapedportion has a convex profile along an optical axis of the intraocularlens; and wherein the saddle-shaped portion has a concave profile in aplane perpendicular to the optical axis of the intraocular lens.
 5. Theintraocular lens of claim 4, wherein the convex profile is a continuouscurve.
 6. The intraocular lens of claim 4, wherein the convex profileincludes at least one straight portion inclined with respect to theplane perpendicular to the optical axis of the intraocular lens.
 7. Theintraocular lens of claim 4, wherein the convex profile includes atleast one straight portion parallel to the optical axis of theintraocular lens.
 8. The intraocular lens of claim 4, wherein theconcave profile has a deepest portion.
 9. The intraocular lens of claim8, wherein the deepest portion is located away from a plane locatedhalfway between an anterior surface and a posterior surface of theadjustable optic.
 10. The intraocular lens of claim 9, wherein thedeepest portion is located closer to an anterior surface than to aposterior surface of the adjustable optic.
 11. The intraocular lens ofclaim 9, wherein the deepest portion is located closer to a posteriorsurface than to an anterior surface of the adjustable optic.
 12. Theintraocular lens of claim 4, wherein the concave profile is a continuouscurve.
 13. The intraocular lens of claim 4, wherein the concave profileis concentric with the optical axis of the intraocular lens.
 14. Theintraocular lens of claim 1, wherein the haptic is stiffer than theadjustable optic.
 15. The intraocular lens of claim 1, wherein thehaptic has a stiffness greater than 500 kPa.
 16. The intraocular lens ofclaim 1, wherein the adjustable optic has a stiffness less than 500 kPa.17. The intraocular lens of claim 16, wherein the adjustable optic has astiffness between 0.5 kPa and 500 kPa.
 18. The intraocular lens of claim17, wherein the adjustable optic has a stiffness between 25 kPa and 200kPa.
 19. The intraocular lens of claim 18, wherein the adjustable optichas a stiffness between 25 kPa and 50 kPa.
 20. The intraocular lens ofclaim 1, wherein the haptic comprises at least two materials havingdifferent stiffnesses.
 21. The intraocular lens of claim 1, wherein thehaptic has essentially the same refractive index as the adjustableoptic.
 22. The intraocular lens of claim 1, wherein the haptic includesa plurality of radial segments that are shaped to conform to anequatorial region of the capsular bag.
 23. An intraocular lens forimplantation in a capsular bag of an eye, comprising: an adjustableoptic having an optic stiffness and an optic refractive index; and ahaptic having a haptic stiffness and a haptic refractive index forcoupling the adjustable optic to the capsular bag; wherein the hapticstiffness is greater than the optic stiffness; and wherein the hapticrefractive index is essentially equal to the optic refractive index. 24.The intraocular lens of claim 23, wherein the haptic stiffness isgreater than the optic stiffness by at least a factor of two.
 25. Theintraocular lens of claim 23, wherein the haptic stiffness is greaterthan 500 kPa.
 26. The intraocular lens of claim 23, wherein the opticstiffness is less than 500 kPa.
 27. The intraocular lens of claim 26,wherein the optic stiffness is between 25 kPa and 50 kPa.
 28. A methodof adjusting the focus of an intraocular lens having an adjustable optichaving an annular recess, comprising: applying a deforming force througha haptic in contact with the annular recess of the adjustable optic; andaltering at least one parameter of the adjustable optic in response tothe deforming force.
 29. The method of claim 28, wherein the at leastone parameter comprises an anterior radius of curvature of theadjustable optic.
 30. The method of claim 28, wherein the at least oneparameter comprises a posterior radius of curvature of the adjustableoptic.
 31. The method of claim 28, wherein the at least one parametercomprises a thickness of the adjustable optic.
 32. The method of claim28, further comprising: applying the deforming force to create anasymmetric deformation of the adjustable optic.